The present invention pertains to an axial piston fluid pump and, more particularly, to a pump having an improved swashplate assembly which substantially simplifies the manufacture and assembly of the pump and provides improved operation and load distribution.
Axial piston pumps are old and well known in the art. All such pumps include a swashplate or tilt plate against which the axial piston ends bear and around which such ends rotate with the angled surface of the swashplate allowing a cyclic reciprocal movement of the pistons providing each cylinder with low pressure intake and high pressure discharge of hydraulic fluid on each rotation. The swashplate or tilt plate is journaled for rotation on a tilt axis transverse to the common axis of the drive shaft the cylindrical rotor housing the pistons. Two typical constructions are utilized in the prior art to support and journal the swashplate for tilting movement.
In one prior art construction the swashplate includes a pair of axially aligned trunions extending from opposite sides of the plate, which trunions are journaled for rotation in the cylindrical sidewall of the pump housing. This construction requires relatively large access ports in the housing sidewall to hold the trunion support bearings and to facilitate assembly. A typical construction of an axial piston pump having a swashplate with integral outboard trunions is shown in U.S. Pat. No. 3,175,510.
The other common pump construction utilizes a cradled swashplate in which a relatively large diameter concave bearing surface is attached to the inside of the pump housing end wall and cradles therein a swashplate having a pair of convex bearing surfaces on opposite sides of the pump drive shaft, which surfaces are rotatably supported in the concave bearing cradle for rocking movement. The large diameter bearing surfaces are difficult and costly to machine accurately. The assembly is also generally complex and includes a relatively large number of machined parts. Such a construction is shown, for example, in U.S. Pat. No. 3,682,044.